base64.cpp

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// base64.cpp: implementation of the Cbase64 class.
//
//////////////////////////////////////////////////////////////////////

#include "stdafx.h"
#include "base64.h"

#ifdef _DEBUG
#undef THIS_FILE
static char THIS_FILE[]=__FILE__;
#define new DEBUG_NEW
#endif

//////////////////////////////////////////////////////////////////////
// Construction/Destruction
//////////////////////////////////////////////////////////////////////

Cbase64::Cbase64()
{

}

Cbase64::~Cbase64()
{

}

int Cbase64::Encode(char *Inbuf, char *Outbuf, int nInLen, int nOutLen)
{
	char table[65]="ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/";

	unsigned char c80,c81,c82,c6;
	int i,k,len;

	if((nInLen*4)>(nOutLen*3+3))
		return 1;

	k=nInLen/3;
	len=k*4;//real outpur string length
	for(i=0;i<k;i++)
	{
		c80=Inbuf[i*3];
		c6= c80 >> 2;
		Outbuf[i*4]=table[c6 & 0x3f];

		c80 = (c80<<4) & 0x30;
		c81 = Inbuf[i*3+1];
		c6  = (c81>>4) & 0x0f;
		Outbuf[i*4+1]=table[c80 | c6];

		c81 = (c81<<2) & 0x3c;
		c82 = Inbuf[i*3+2];
		c6  = (c82>>6) & 0x03;
		Outbuf[i*4+2]=table[c81 | c6];

		Outbuf[i*4+3]=table[c82 & 0x3f];

	}

	i=nInLen%3;
	k=nInLen/3;
	if(i)//some more.
	{
		len+=4;

		c80=Inbuf[k*3];
		c6= c80 >> 2;
		Outbuf[k*4]=table[c6 & 0x3f];

		if(k==1)
		{
			c80 = (c80<<4) & 0x30;
			Outbuf[k*4+1]=table[c80];
			
			Outbuf[k*4+2]='=';			
		}
		else
		{
			c80 = (c80<<4) & 0x30;
			c81 = Inbuf[k*3+1];
			c6  = (c81>>4) & 0x0f;
			Outbuf[k*4+1]=table[c80 | c6];

			c81 = (c81<<2) & 0x3c;
			Outbuf[k*4+2]=table[c81];			
		}

		Outbuf[k*4+3]='=';
	}//end of some more.

	Outbuf[len]='\0';

	return len;
}

int Cbase64::Decode(char *Inbuf, char *Outbuf, int nInLen, int nOutLen)
{
    int nbytesdecoded;
    char *pBufin;
    unsigned char *pszBufout;
    unsigned char szBufout[256];
    char szBufTmp[350];
    int nprbytes;
	DWORD dwCoded=nInLen;
	char *pszCoded=Inbuf;
	char *pszDecoded=Outbuf;

	const int pr2six[256]={
		64,64,64,64,64,64,64,64,64,64,64,64,64,64,64,64,64,64,64,64,64,64,64,64,
		64,64,64,64,64,64,64,64,64,64,64,64,64,64,64,64,64,64,64,62,64,64,64,63,
		52,53,54,55,56,57,58,59,60,61,64,64,64,64,64,64,64,0,1,2,3,4,5,6,7,8,9,
		10,11,12,13,14,15,16,17,18,19,20,21,22,23,24,25,64,64,64,64,64,64,26,27,
		28,29,30,31,32,33,34,35,36,37,38,39,40,41,42,43,44,45,46,47,48,49,50,51,
		64,64,64,64,64,64,64,64,64,64,64,64,64,64,64,64,64,64,64,64,64,64,64,64,
		64,64,64,64,64,64,64,64,64,64,64,64,64,64,64,64,64,64,64,64,64,64,64,64,
		64,64,64,64,64,64,64,64,64,64,64,64,64,64,64,64,64,64,64,64,64,64,64,64,
		64,64,64,64,64,64,64,64,64,64,64,64,64,64,64,64,64,64,64,64,64,64,64,64,
		64,64,64,64,64,64,64,64,64,64,64,64,64,64,64,64,64,64,64,64,64,64,64,64,
		64,64,64,64,64,64,64,64,64,64,64,64,64
	};

    //
    // Remove leading whitespace.
    //
    while( ( dwCoded > 0 ) && ( isspace( *pszCoded ) ) )
    {
        pszCoded++; dwCoded--;
    }

    if ( dwCoded > ( 350 - 4 ) )
        return 1;

    strncpy(szBufTmp, pszCoded, dwCoded);
    szBufTmp[dwCoded] = szBufTmp[dwCoded+1] = szBufTmp[dwCoded+2]
                      = szBufTmp[dwCoded+3] = 0;

    //
    // Determine how many characters are in the input buffer.
    // If this would decode into more bytes than would fit into
    // the output buffer, return 2
    //

    pBufin = szBufTmp;
    while( pr2six[ *( pBufin++ ) ] <= 63 );
    nprbytes = pBufin - szBufTmp - 1;
    nbytesdecoded = ( ( nprbytes + 3 ) / 4 ) * 3;

	if(nOutLen<nbytesdecoded)
		return 2;

	if ( nbytesdecoded > (256 - 4) )
        return 2;

    pszBufout = (unsigned char *) szBufout;

    pBufin = szBufTmp;

    while (nprbytes > 0) {
        *(pszBufout++) =
            (unsigned char) (pr2six[*pBufin] << 2 | pr2six[pBufin[1]] >> 4);
        *(pszBufout++) =
            (unsigned char) (pr2six[pBufin[1]] << 4 | pr2six[pBufin[2]] >> 2);
        *(pszBufout++) =
            (unsigned char) (pr2six[pBufin[2]] << 6 | pr2six[pBufin[3]]);
        pBufin += 4;
        nprbytes -= 4;
    }

    if(nprbytes & 03) {
        if(pr2six[pBufin[-2]] > 63)
            nbytesdecoded -= 2;
        else
            nbytesdecoded -= 1;
    }

    szBufout[nbytesdecoded] = '\0';
	
    strcpy(pszDecoded, (char*)szBufout);

    return nbytesdecoded;
}